Arizona Republican Sen. John McCain, who died of brain cancer Aug. 25, once championed the fight against climate change on the Senate floor and in his presidential campaign a decade ago.

Years before climate change became a signature issue for President Barack Obama, McCain prodded both parties to set mandatory caps on U.S. greenhouse gas emissions.

In August 2001, he warned Senate colleagues that a scientific consensus was emerging that global temperatures were on the rise and glaciers were in retreat and “that there is new and stronger evidence that most of the observed warming over the 50 years is attributable to human activities.”

A year later, he and Connecticut Sen. Joe Lieberman, then a Democrat and later an Independent, introduced a cap-and-trade bill, which would have put a cap on emissions and allowed companies to buy and sell allowances to emit certain amounts.

The Senate voted down versions of their bill in 2003 and again in 2005. An effort by Obama and the then-Democratic-led Senate to get cap and trade across the finish line in 2010 died without a floor vote.

When McCain won the Republican Party’s presidential nomination in 2008 to face off against Obama, it was the first time both candidates for the presidency backed legislation to cap U.S. emissions. The Republican platform then called for “technology driven, market-based solutions that will decrease emissions, reduce excess greenhouse gases in the atmosphere, increase energy efficiency” and mitigate climate impacts.

But McCain eventually soured on Obama’s attempt to use the Environmental Protection Agency and other regulatory agencies to address emissions. He voted in 2010 to overturn EPA’s endangerment finding that greenhouse gases threaten health and human welfare. That proposal, by Sen. Lisa Murkowski (R-Alaska), fell just shy of passage in a 47-53 vote.

Methane Vote a Rare Rebuke

But McCain’s reputation as a maverick was again evident on the floor in May 2017 during a GOP-led effort to repeal limits of methane, a potent greenhouse gas, using the Congressional Review Act.

The Republican-controlled Congress and President Donald Trump used that law more than a dozen times to kill final Obama rules, including several environmental regulations. But McCain was a surprise “no” vote, and the effort to kill the rule was defeated 49-51. It was the only Republican-led resolution targeting an Obama regulation to fail in the current session of Congress.

McCain noted the law bars agencies from issuing any future rules that are substantially similar to those repealed by Congress under the law.

“Improving the control of methane emissions is an important public health and air quality issue,” McCain said in a statement after the vote.

Mark Brownstein, senior vice president of the climate and energy program at the Environmental Defense Fund, said at the time that “John McCain demonstrates that he is a voice of common sense and reason in the Senate.”

McCain also was among the few Republicans who didn’t back Trump’s decision to pull the U.S. out of the 2015 Paris climate deal.

“I would have liked to fix the problems rather than junk the whole thing,” he told Bloomberg Environment at the time.

Other Issues

McCain drew attention for his work on other energy and environment issues. The National Park Service and Grand Canyon Association in April honored McCain and former Arizona Democratic Rep. Morris Udall for their work on preserving the Grand Canyon.

Citizens for Responsible Environmental Solutions, a group formed to engage Republicans policymakers on energy issues, cited the senator’s work to fund repairs of the water intake system at Willow Beach National Fish Hatchery near Hoover Dam, as well as provide $50 million for water conservation projects at Colorado River storage reservoirs.

“McCain has amassed a clean energy legacy that will protect the natural environment and strengthen the nation’s economy for future generations,” the group said on its website.